Rotate current selection of Objects .. Each object with a different Random Rotation ... Is this built into Blender?
You can do this using proportional edit mode.
If you have some objects in a scene that is already built and you need to do this operation without affecting anything else, first select your objects.

Press / to enter local view.  This will isolate these objects.

Change your tool settings to operate on individual origins, and set proportional edit to random.

You can now select one object and rotate it, with a large enough proportional edit strength, you will begin rotating each object a proportional amount to the rotation of the one you've selected.

Press / again to return to normal view.